Project objective
Hydro-ecological systems include innovative grey and green infrastructure, such as systems of spatially distributed detention basins and renaturation of wetlands as local water retaining measures. Conventional frequency analysis of extremes and time series-based planning of hydro-ecological systems were up to recently based and still rely on the stationarity principle. However, these methods, given the ongoing and expected gradually occurring changes in land use and climate, may not ensure the required performance, necessary reliability and safety of hydro-ecological systems throughout their future lifespan. While there are new nonstationary frequency analysis techniques, these only apply to limited planning problems, mostly of hydraulic structural systems (e.g. flood release structures). For simulation-based planning in the time domain when the driving hydrometeorological time series' stochastic features and the catchment's properties progressively change, frameworks for planning and evaluating the uncertainty of a system's performance and risk of failures (e.g. various storages for ecosystem restoration and slowing down runoff), are missing.
Therefore, the project intends to develop the scientific basis for a future toolbox of methodologies and models for improving the evaluation of the performance of hydro-ecological hydrological systems under changing boundary conditions in the unique setting of the Slovak Carpathians. In particular, it will focus on creating the scientific basis for planning using the time series-based simulation of hydro-ecological systems by utilizing current stochastic and deterministic modelling methods to imitate non-stationarity by slowly and gradually changing environmental conditions. A concept of stepwise changes in stationary environmental conditions is foreseen to provide such a simulation framework. The core premise is that the nonstationary regime of hydrometeorological processes can be regarded as a reflection of slow stepwise quasi-stationary periods, represented in simulation studies by a sequence of adequately parameterized simulated time series created by models consisting of weather generators coupled with rainfall-runoff models. We propose to use multivariate copula-based dependence modelling to describe these stepwise stationary periods contrary to conventionally used univariate statistical methods. To ensure that the outputs of conceptual rainfall-runoff models and stochastic weather generators, combined into a framework, can replicate the changes in dependencies in the observed time series, new models' structures and parametrizations must be developed.
A coherent, integrated set of simulation tools based on remote sensing (satellite and laser scanning, digital photogrammetry, ultrasonic sensing, etc.), field surveys, data collection and means of new statistical data analysis and hydrological and hydraulic mathematical modelling approaches are required to create the knowledge relevant to estimate the long-term efficiency of such systems under changing conditions. To identify temporal fluctuations of the auto-dependencies in hydrometeorological time series in a slowly changing environment and to help identify their causes, uni- and multivariate statistics will be tested and implemented, and adequate stochastic weather generators will be developed.
These and the new rainfall-runoff and flood-routing hydrologic models will be integrated for simulating ensembles of the baseline and anticipated future hydrometeorological time series evaluating their performance and assessing the uncertainty of the outcomes. Planning in the project's pilot catchments will demonstrate how to assess the uncertainties and hazards of failure of hydro-ecological systems based on ensembles of simulations. Such new information and knowledge resources would help these environmentally sound interventions using hydro-ecological systems become more widely accepted and efficient.